1. Field of the Invention
The present invention relates to a technology for taking backup of data.
2. Description of the Related Art
A known technique in which redundant data is stored in a plurality of Hard Disk Drives (HDDs) enables protection of data, because if data in one HDD is lost, it can be recovered from other HDD.
However, recently, there has been a substantial increase in the amount of data that needs to be stored in HDDs. Consequently, the time required for backup of the data has also increased substantially. Thus, there is a need of a technology that can efficiently perform the backup operation. Japanese Patent Publication No 2001-166974 discloses an advanced copy function, in other words, a Point-in-Time (PIT) copy function to carry out backup of data.
FIG. 14 is a schematic for explaining the advanced copy function. A destination disk is prepared that has the same amount of storage capacity as the amount of source data to be copied. Then the entire source data is transferred from a source disk to the destination HDD. Finally, the data in the destination disk is used to perform backup. Once the source data is transferred from the source disk to the destination disk, the source disk and the destination disk can be logically separated from each other, so that other operations can be performed while data is being backed up from the destination disk. However, because it is necessary to prepare the destination disk, it leads to increased costs. Moreover, if there are a large number of HDDs that are to be backed up, the same number of destination disks are also required, which leads to further increase in the costs.
In other words, there is a need of a technology that supports the advanced copy function but that is inexpensive.